Fastening device



Feb. 21, 1950 R, HALLOCK 2,498,627

FASTENING DEVICE Filed Jan.- 26, 1944 3 Sheets-Sheet 1 w W3 @K 1; TTOHNEY Feb. 21, 1950 R. 1.. HALLOCK FASTENING DEVICE 3 Sheets-Sheet 2 Filed Jan. 26, 1944 ATTORNEY Feb. 21, 1950 R. L. HALLOCK 2,498,627

FASTENING DEVICE Filed Jan. 26, 1944 3 Sheets-Sheet 3 Patented Feb. 21, 1950 FASTENING DEVICE Robert Lay Hallock, Larchmont, N. Y., assignor to Elastic Stop Nut Corporation of America, Union Township, N. J a corporation of New Jersey Application January 26, 1944, Serial No. 519,729

29 Claims. 1

The present invention relates to fastening devices and has particular reference to fastening devices of the kind intended tobe driven or pushed into material and generally considered as nails, by which term the device of the present invention will hereinafter, without limitation, be referred to. More particularly the invention relates to self-locking nails, that is nails so constructed that when installed they cannot be with drawn from the material inthe manner of an ordinary nail but can be removed only by tearing out a substantial area of the material in which they are fastened.

Comparatively recent developments in the building and allied industries have resulted in the increasing use of relatively soft fibrous materials for wallboards, siding and like uses and other materials of relatively soft nature are being increasingly utilized for insulating and other purposes. In many of such uses it is necessary for other materials to be fastened to the relatively soft material, as for example the fastening of shingles to siding and the fastening of sheet roofing material such as asphalt sheet to roof sheathing. In most instances the soft fibrous m aterial is not sufliciently dense or strong to adequately grip a nail and heretofore it has been the practice to either drive nails entirely through the material and clinch them on the reverse side or secure them against withdrawal by use of a washer or other locking means secured to the portion of the nail projecting from the reverse side of the material. Such procedures are relatively slow and costly and moreover require that access be had simultaneously to both sides of the wall. I

It is accordingly the general object of the present invention to provide a new and improved kind of fastening device or nail which is usable in the manner of the ordinary nail by being either driven by hammer or pushed into the material to be fastened and which when installed will lock itself in or behind the material, so that even though the material in which it is installed is relatively weak, the nail cannot be withdrawn without tearing out a substantial area of the material. A further object is the provision of a novel nail in which the locking action is effected entirely by the force necessary to drive the nail to installed position so that the desired locked installation can be effected when access is available to only one side of the material. Still another object is to provide a self-locking nail which will when installed exert a compressive force tending to pull together the parts fas- 2 tened. A still further object is to provide a nail which will accomplish the desired object and which can readily be manufactured cheaply on a mass production basis and sold at prices comparable to those of conventional nails.

In order to achieve the above-mentioned objects and other and more detailed objects which will hereinafter appear the invention contemplates provision of a nail, preferably formed from sheet metal, characterized by coacting tension and compression portions or members so united and arranged that upon installation of the nail the tension member operates in conjunction with the force required to install the nail to cause the nail, and particularly the compression member of the nail, to bend or buckle so that in the finally installed position of the nail it is spread laterally in the material to a form preventing its withdrawal from the material without tearing out a substantial section of the latter.

The principles of the invention may be embodied in a wide variety of specific forms and for a better understanding of the more detailed na-' ture of the invention and the manner in which it may be utilized in practical embodiments, reference may best be had to the ensuing portion of this specification, taken in conjunction with accompanying drawings, in which are described and illustrated, by way of example but without limitation, several forms of nail embodying the invention.

In the drawings:

Fig. 1 is a sectional view partly in elevation of w a nail embodying the invention, and partially driven to secure one piece of material to another;

Fig. 2 is a view similar to Fig. 1 showing the nail in installed position;

Fig. 3 is an elevation on enlarged scale showing the nail illustrated in Fig. 1;

Fig. 4 is a view looking from the left of Fig. 3;

Fig. 5 is a plan view showing the blank from which the nail shown in the preceding figures is formed;

Fig. 5a is a fragmentary view similar to Fig. 5 showing a portion of a blank for a nail of the general type shown in Figs. 1 to 5 but having a different form of head;

Fig. 5b is a view showing the head portion of the nail formed from the blank shown in Fig. 50;

Fig. 6 is a perspective view of a different form of nail embodying the invention;

Fig. 7 is a plan view of the blank-from which the nail of Fig. 6 is formed;

Fig. 8 is a section taken on the line 8-8 of Fig. 6;

Fig. 9.is a side view showing the form taken by the nail shown in Fig. 6, after it is installed; I

Fig. is a side view of still another form of ii embod n the invention; Fig. 11 is e v iew showing the nail installed;

Fig. 12 is a View of the blank from which the nail ofv Fig. 10 is formed;

Figs. 13 and 14 are plan and elevation views respectively of the head portion of the nail of F1 10;

gig. 15 is an elevation of still another form of nail embodying the invention;

Fig. 16 shows the nail of Fig. 15 installed;

Fig. 1'7 is a view of the blank from which the nail of Fig. 15 is formed;

Fig. 18 is a view showing the blank from which still another nail is formed;

Fig. 19 is a view showing the nail formed from the blank of Fig. 18;

Fig. 20 shows the nail of Fig. 19 installed;

Fig. 21 is a top view of the nail of Fig. 19;

Fig. 22 is a section on line 22-22 of Fig. 19:

Fig. 23 is a section showing still another form of nail partially installed;

Fig. 24 shows the nail of Fig. 23 fully installed;

Fig. 25 is a view of the nail taken at right angles toFi 23; and

Fig. 26 is a view of the blank forming the nail of Fig. 23.

Referring now to the form of nail shown in Figs. 1 to 5 inclusive, and more particularly to Fig. 5, the nail comprises an integral body designated generally at in which is stamped or otherwise formed from sheet metal or other suitable material. The body Ill is of generally triangular configuration and is sheared so as to approximately blsect the blank along the line l2 which extends from the head end of the blank to a point In spaced from the sharpened or pointed end of the blank. The shear line I2 divides the body into two portions i4 and I6 united at the point i2a. As will hereinafter appear the part I4 constitutes a tension portion or member and the part Hi constitutes a compression portion or member. The outer edge of the tension member i4 is shaped to provide a generally triangular-shaped projecting lip i8 and the edge is advantageously slightly recessed at the point 20 adjacent to the bottom of the lip. A circular projection 22 is formed adjacent to the lip i8 and a diamond-shaped depression 24 extending longitudinally of the part I is formed between the projection 22 and the headend of the part.

The compression portion I6 is formed with a longitudinally-extending stiffening rib 26 which terminates short of the head end of the part and also terminates a substantial distance short of the As will be seen more clearly from Figs. 3 and 4 the blank is then shaped by offsetting the part It at 32, adjacent to the place where the two parts are united, and bending the ofiset parts so that one overlies the other with the projection 22 on the part M received in the recess formed by the stiffening rib 28 on the part is. The lip is is bent over to engage the face of the part it at the side of the stiffening rib 2B. The head end of the part I4 is bent over to form a fiat head 36 and for reasons hereinafter pointed out this portion is bent over to somewhat more than a right angle from the plane of the main portion of part It. The depressed portion 24 provides 'a stiflening fillet 36 of generally triangular shape as seen more clearly in Fig. 3. The head end of the compression part i6 is curved as will be seen from Figs. 3 and 4' to provide a U-shaped head 38 adapted to be struck by a hammer or other impact tool without danger of the latter glancing oif.

Referring now more particularly to Figs. 1 and 2 the operation of the nail will be more or less apparent. In these figures the nail is shown as applied to fasten a sheet of relatively hard material such for example as an asbestos shingle Ml having a preformed nail hole 42 to a body of relatively soft material such as a board of fiber sheathing or the like 44. The nail is inserted through the hole 62 and then struck with a hammer in the manner of driving an ordinary nail. The hammer blow causes the nail to penetrate the material without distortion to the position shown in Fig.1 at which time the head 34 of the tension member, which constitutes an abutment, contacts the surface of the shingle 40 and arrests further longitudinal inward movement or penetration of the material 54 by the tension member. The impact of the blow, however, causes the compression member, the head of which still projects from the surface 30, to continue to move inwardly relative to the tension member. Due to the stiffening ribs 26 and 30 the upper and lower portions of the compression member do not distort under compression but the transverse rib 28, which provides a weakened section, causes the compression member to bend or buckle intermediate its ends and force the embedded portions of the two members away from each other so that in effect the nail is laterally spread within the material it, as shown in Fig. 2. During this spreading operation the head ends of the compression and tension members are held together by the lip it as well as by the action of the wall of the opening 42. Also before and during the installing operation the two parts of the nail are restrained against lateral movement relative to each other at the head end, b the projection 22 which remains in the groove left by the projection 26, until the two parts are forced apart near the end of the installing operation.

As will be observed from Fig. 2 the bending of the compression member which except for the weakened place 28 is stiffer than the tension member, tends to push the tension member to an inclined position relative to the plane of the surface through which the nail is driven. It is for this reason that the head 34 on the tension member is bent over to somewhat more than a right angle, so that in the finally installed position this head will lie flat against the surface it abuts. As will also be observed from Fig. 2 the stiffened portion of the compression member bends the sharpened or point portion 46, below the place l2a where the tension and compression members are united, so that this point portion projects laterally beyond the triangle'formed by the tension member and the buckled compression member. Thus a very considerable extent of lateral spread of the nail in the material is obtained and as will be apparent from Fig. 2 the shingle Ml cannot be pulled away from the material it unless sufilcient force is applied to cause the nail to tear out a very substantial section of the material in which it is embedded.

By reference to Figs. 1 and 2 it will be observed that when the nail spreads as it moves to its finally installed position, the portion below the weakened place 28 in effect swings in an arc about this place as a pivot and compresses the material in front of it to exert a substantial force tending to draw the two fastened parts together. The wedging action due to the spreading apart of the tension and compression members also contributes to this action.

It is also to be noted that any force applied to the shingle 40 or any withdrawing force applied by pliers, a screwdriver or the like tending to pull the head 34 away from the surface of the shingle 40 will not serve in any way to tend to collapse the deformed nail but will on the contrary tend to keep it in its spread form. Thehead 38, being substantially flush with the surface of the shingle 40 offers no means of being pulled and no force applied to the shingle 48 will tend to pull the head 38 outwardly so as to straighten the buckled compression member I5.

In the foregoing description the specific steps for forming the nail have not been described in detail since they are simple stamping and forming operations readily performed by anyone skilled in the sheet metal art. Preferably the device is formed in an ordinary transfer press having a series of progressive dies which form and shape the metal.

In Figs. a and 5b a form of nail is shown which in all respects is similar to the form just described except for the head for the compression member. In this form the compression member "5a is somewhat longer in the blank than the tension member l4 and the extended head end of member I6a is bent over as shown in Fig. 5b to form a flat head 38a which when installed abuts the surface against which the head 34 abuts. As the head 38a is driven home it is bent along the line 38b to lie flat against the surface, the head being bent over beyond a right angle when the nail is formed in order to provide a striking surface along the line 38b for driving the nail.

The form shown in Figs. 5a and 5b provides a larger head area than can be obtained as conveniently with the form shown in Figs. 1 to 5 in which all of the head area is provided by the tension member. Also in case for any reason it should be desirable, the form shown in Figs. 5a and 51; offers the possibility of withdrawal by pulling on the head 38a. while holding the head 34 against the surface of the material, thus tending to straighten the buckled compression member. Even with this arrangement, however, the holding power of the nail is not impaired from the standpoint of withstanding a force tending to pull a part such as the shingle 40 away from the soft material. If such a force is applied it will.

be transmitted to both heads and will not result in any force tending to straighten out the nail.

While in the example just described the nail has been shown as applied to parts consisting of a surface part having a preformed hole and a part of soft material thicker than the length of the nail, it will be apparent that the utility of the nail is not limited to such application. The stiffened point portion of the nail permits the nail to be driven through any reasonably soft material without the compression member buckling before it is forced to buckle by the action of the tension member. Thus the nail is readily usable for nailing material such as asphalt roofing sheets and the like to soft sheathing, without the sheets being previously perforated; also it will be apparent that the final form taken by the nail as shown in Fig. 2 is such that it will lock and hold even if the nail projects entirely through the material into which the nail is driven so that the turned over part of the nail projects from the rear face of the material. This is largely due to the generally wedge-shaped or triangular form which the nail takes in its installed position, and the point portion 46 will abut against the rear face of the material and must be pulled through it the same as if the nail were entirely embedded in the material.

Referring now to Figs. 6 to 9, a form of nail embodying the invention is shown which employs two tension members together with a single compression member.

In this form the body 50 is slit along the shear lines 52 and 54 to provide a compression member 56 and two tension members 58 and 68. The shear line 52 runs from the head end of the nail to an opening 82 while the shear line 54 runs from the head end to a like opening 64. Between and slightly above openings 62 and 64 there is a small hole 66 from which a shear line 68 runs to the point of the body, bisecting the pointed end. Between the opening 62 and the outer edge of the body a web 10 is formed and a like web I2 is formed between the opening 84 and the adjacent edge of the body. A web 14 is formed between the opening 62 and the shear line 68 and'a similar web 16 is formed between the opening 84 and shear line 68. The tension members are reversely bent along the lines 18 and respectively to lie against the compression member 56 as shown in Fig. 6; also the head ends of the tension members are bent over to provide heads 82 and 84 respectively, these heads advantageously being reinforced by fillets one of which appears at 86 in Fig. 6. The compression member is stiffened by longitudinal ribs 88 and 88.

If it is assumed that the nail as shown in Fig. 6 has been driven into material until the heads 82 and 84 abut the surface it will be seen that the head end of the compression member extends above the surface and that when driven so that this head is flush with the heads 82 and 84 the nail must be distorted.

By reference to Fig. 7 it will be seen that if the compression member 56, which includes the portion stiffened by the ribs 88 and 90 and the webs I4 and 16, is moved longitudinally relative to the tension members 58 and 60 which terminate in the webs l0 and 12, the compression member will bend or buckle at the relatively weak places adjacent to the hole 66, the point portions of the nail being pulled away from each other or spread by the pull of the tension membars to a shape as seen in Fig. 9. For purposes of illustration the point portions 92 and 84 have been shown in the same plane as the plane of the compression member 58 but in practice, due to the fact that the tension webs l0 and 12 lie in planes different from the plane of the compression webs l4 and 16, the points 92 and 94 will be pulled outwardly to lie in a plane oblique with respect to the plane of the compression member. It will be noted, however, that in this form of nail the same basic principle operates to cause the nail to spread to lock itself, the spreading action being effected by the tension of members the motion of which is arrested by abutment heads and which after being arrested cause the bending or buckling of a compression member moving relative to the tension members, to secure the desired spreading effect.

In Figs. 10 through 14 a form of nail is shown having one tension member and two compression ber 204 and a compression member 206.

members. In this form the body indicated generally at I is blanked to provide a tension member I02 having a head I04 which by a suitable stamping or coining operation is shaped to form a disc-like head having open slots I06 and I08, as seen in Figs. 13 and 14. The blank is further formed to provide compression members I I0 and H2. Member H0 is provided with notches lid and H6 and member II2 is provided with similar notches H0 and I20. The tension member I02 is twisted through a right angle as indicated at I22 in Fig. 10 and the head ends of the compression members H0 and I I2 are inserted in the slots I06 and I08 of head I04, the final form of the nail being shown in Fig. 10. The action of the nail is more or less obvious from Fig. 11 since upon abutment of the head I04 against the surface of a shingle or the like 40, further inward movement of this member is arrested and the compression members are caused to buckle, to spread and lock the device, due to the weakened sections of these members provided by the respective notches.

In Figs. 15 to 17 another form is shown having a single compression member and two tension members. In this form the body I50 is out along shear lines I52 and I54 to provide a compression member I56 and two tension members I50 and I60 the head ends of which are bent over to form heads I62 and I64 respectively. Near the lower ends of the shear lines I52 and I54 holes I66 and I68 are provided to form a weakened section in the compression member at I10 intermediate the ends of this member. The head end of the compression member I56 is bent over to form a head I12, this head being bent in the direction opposite that in which the heads I62 and I64 of the tension members are bent. As will be apparent from Figs. 15 and 16 the action of the nail when installed is similar to that previously described. Heads I62 and I64 abut against the surface of the body into which the nail is driven and the further movement of the head I12 causes the compression member to buckle at point I10 as indicated in Fig. 16. Advantageously the compression member is shouldered at I14, at the base of the head portion I12, so that when the shoulders I14 pass the lower edges of the heads I 62 and I64, the latter, due to inherent tension or pressure exerted by the material into which the nail is driven, snap over these shoulders to form a lock preventing the head I12 from being drawn by pliers or otherwise in a way which will tend to straighten the nail and permit its withdrawal.

In Figs. 18 to 22 another form of nail is shown having one compression member and one tension member. In this form the body 200 is sheared along line 202 to provide a tension mem- The latter member is notched on its outer edge at 208. The tension member is punched to provide an opening 2I0 at its head end and this end is bent over and the main portion of this member is also bent to U-shaped form, as seen more clearly in Figs. 21 and 22 so that the head end of the compression member 206 passes through the slot formed by the opening 2I0 in the head 2I2. The action is in this instance, the same as before described, the abutment of the head 2I2 against the surface of the body 40 causing further movement of the compression member to buckle the latter at the notch 208, to spread the two members and to cause the pointed end portion 2 I 4 of the nail to project laterally.

In Figs. 23 to 26 a form of nail is shown particularly adapted for use in fastening coverings to upholstery and the like. This form is particularly useful for use with very soft materials, such as cotton or other upholstering materials and is intended primarily for installation by pushing in the manner of a thumbtack. In this form the body 250 which advantageously is of brass or other relatively easily deformable material is slit along the line 262 to provide a compression member 254 and a tension member 258. The latter member is cut to provide a head 2'68 slotted at 260, th head being bent over. The tension member is ofiset at 202 as shown in Fig. 23 and the compression member is transversely bent at 264 to provide a weakened section. The compression member is also provided by any suitable means of attachment with a head 266 which preferably is of the usual form for finishing nails of the upholstery type. The action is as previously described, the abutment of the head 258 of the tension member causing further inward movement of the compression member to buckle the latter so that the nail assumes the position shown in Fig. 24. Advantageously the head 258 of the tension member is shaped so that in coaction with a head 266 on the compression member which is slightly yieldable, the latter head may be snapped over the former, as shown in Fig. 24, to provide a catch or look for preventing the head 266 from being pulled away from the head 258 and thus tending to straighten the nail from the shape shown in Fig. 24 to the shape shown inFig. 23.

From the foregoing description of the several different embodiments herein illustrated by way of. example itwill be apparent that theprinciples of the invention may be embodied in a very wide variety of specific forms of nail and the invention is accordingly to be considered as not limited in its scope to the forms shown but to embrace all forms of device coming within the scope of the appended claims.

What is claimed is:

1. A nail comprisingan integral sheet metal body having a substantially fiat sharp penetrating end portion, a tension member and a compression member separate from the tension member extending from said end portion, said members being ofiset relative to each other above said end portion to lie in diiTerent contiguous substantially parallel planes and overlap each other at least in part, said tension member being shorter than said compression member and having a portion bent outwardly to provide a material engaging abutment and said compression member being formed to provide a place intermediate its ends relatively weak in resistance to compression for causing the compression member to bend to spread the inner portion of the device after penetrative movement has been arrested by the action of said abutment.

2. A device as set forth in claim 1 in which said relatively Weak place is provided by a rib formed in said sheet metal to provide a trough 3. A fastening device comprising an integral where they are united, said tension member being shorter than said compression member and having a portion bent outwardly to provide a material engaging abutment, said compression member being formed to provide a place intermediate its ends relatively weak in resistance to compression for causing the compression member to bend to spread the inner portion of the device after penetrative movement has been arrested by the action of said abutment, and said compression member further being provided with longitudinally extending stifiening means elsewhere than at said relatively weak place.

4. A fastening device comprising an integral sheet metal body providing an end shaped to penetrate material and tension and compression members united at a place near said end and shaped to extend adjacent to each other from the place where they are united, said tension member being shorter than said compression member and having a portion bent outwardly to provide a material engaging abutment, said compression member being formed to provide a place intermediate its ends relatively weak in resistance to compression for causing the compression member to bend to spread the inner portion of the device after penetrative movement has been arrested by the action of said abutment, and said compression member further being provided with stiffening ribs extending longitudinally from eac side of said relatively weak place.

5. A device as set forth in claim 1 in which the relatively weak place in the compression member is provided by a transversely extending rib and said member is stiffened on each side of said rib by longitudinally extending ribs.

6. A device as set forth in claim 1 in which one of said members is provided with a portion bent back upon itself and over the other member to provide a U-shaped section engaging both sides of said other member and permitting relative sliding movement between the members.

7. A device as set forth in claim 1 in which the tension member is provided with a projection adjacent to its head end bent to slidably engage the compression member.

8. A device as set forth in claim 1 in which said members are provided with means for preventing lateral displacement of the members relative to each other.

9. A device as set forth in claim 1 in which said compression member is formed with a longi tudinally extending stiffening rib and said tension member is provided with a projection extending into the depression resulting from the formation of said rib.

10. A device as set forth in claim 1 in which the portion of said tension member forming said abutment constitutes the head of the member.

11. A device as set forth in claim 1 in which the head end of said tension member is bent outwardly and provided with a stiffening fillet.

12. A device as set forth in claim 1 in which the head end of said tension member is bent outwardly by more than a right angle from the general plane of the member.

13. A device as set forth in claim 1 in which the sheet metal of the compression member is bent at the head end of the nail to form a cross section providing a driving end surface, the perimeter of which embraces a substantial two dimensional area in a plane perpendicular to the longitudinal axis of the member. for engagement by a driving tool. a

14. A device as set forth in claim 1 in which 10 the head end of the compression member is bent to a generally --U-shaped cross section.

15. A device as sej'I forth in claim 1 in which the head ends of both members are bent outwardly by at least right angles from the general planes of the respective members.

16. A device as set forth in claim 1 in which the tension member is offset adjacent to the place where said members are united and said members are bent to overlap each other from said offset.

17. A device as set forth in claim 1 in which said compression member is notched to provide said relatively weak place.

18. A device as set forth in claim 1 in which said tension member is bent to generally U- shaped section to embrace a portion of said compression member.

'19. A device as set forth in claim 1 in which the head end of the tension member is formed to provide a. guide for the compression member.

20. A device as set forth in claim 1 in which both tension and compression members are formed to provide heads'shaped to interlock when the device is installed.

21. A device as set forth in claim 1 in which both tension and compression members are provided with heads and the head on the compression member is constructed to snap over the head on the tension member when the device is installed.

22. A sheet metal blank for a self-locking nail comprising a body having the general shape of an acute triangle and being bifurcated from a place spaced from but near the pointed end to the other end of the blank and further having a generally triangular shaped ear projecting from one side of the body.

23. A sheet metal blank for a self-locking nail comprising a body having the general shape of an acute triangle and being bifurcated from a place spaced from but near the pointed end to the other end of the blank, one of said bifurcations being weakened in compression at a place intermediate its ends.

24. A sheet metal blank for a self-locking nail comprising a body having the general shape of an acute triangle and being bifurcated from a place spaced from but near the pointed end of the other end of the blank, one of said bifurcations being weakened in compression at a place intermediate its ends by a transversely extending rib forming a corresponding transversely extending groove.

25. A sheet metal blank for a self-locking nail comprising a body having the general shape of an acute triangle and being bifurcated from a place spaced from but near the pointed end to the other end of the blank, one of said bifurcations being weakened in compression at a place intermediate its ends by a notch formed at its outer edge.

26. A nail comprising a sheet metal member having two legs of unequal length joined at a vplace intermediate the ends of the nail, one of said legs being shaped to provide an open channel extending longitudinally of the leg between said place and the head end of the nail and the other of said legs having a portion situated in said channel, the shorter one of said legs having a laterally extending abutment at its head end beyond which the head end of the longer leg projects, and means providing a weakened portion II forming a predetermined bending point in the longer leg located between said place where the legs are Joined and the head end of the nail.

27. A nail comprising a sheet metal member having two legs of unequal length connected at a place intermediate the ends of the nail, the longer leg including a weakened portion above said place 01' connection for establishing a predetermined bending point in the leg and being formed with a channel portion extending toward the head end of the nail from said weakened portion to provide a substantially rigid structure above said weakened portion, the shorter leg having a laterally extending material engaging abutment at its head end and the longer leg and the channel therein extending beyond said abutmeni at the head end of the nail.

28. A nail comprising an integral sheet metal body having a substantially fiat sharp penetrating end portion, a tension member and a compression member extending from said end portion, said members being offset relative to each other above said end portion by a fold connecting the members at one side thereof and said members extending separately from said fold in different contiguous substantially parallel planes and overlapping each other at least in part, said tension member being shorter than said compression member and having a portion bent outwardly to provide a material engaging abutment and said compression member being formed to provide a place intermediate its ends relatively weak in resistance to compression for causing the ing the members at one side thereof and said members extending separately from said fold in diflerent contiguous substantially parallel planes and overlapping each other at least in part, said tension member being shorter than said compression member and having a portion bent outwardly to provide a material engaging abutment and said compression member having a relatively weak bendable portion between said fold and the head end of the compression member and a longitudinally channeled and relatively stiffer portion between said bendable portion and the head end of the compression member for causing said compression member to bend at said bendable portion to bend said end portion away from the axis of the nail after penetrative movement of the tension member has been arrested by the action oi said abutment when the nail is fully driven.

ROBERT LAY HALLOCK.

REFERENCES CITED The following references are of record in the iile of this patent:

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